Journal article
Alanine Racemase Free Energy Profiles from Global Analyses of Progress Curves
Journal of the American Chemical Society, Vol.126(24), pp.7464-7475
06/23/2004
DOI: 10.1021/ja049579h
PMID: 15198593
Abstract
Free energy profiles for alanine racemase from Bacillus stearothermophilus have been determined at pH 6.9 and 8.9 from global analysis of racemization progress curves. This required a careful statistical design due to the problems in finding the global minimum in mean square for a system with eight adjustable parameters (i.e., the eight rate constants that describe the stepwise chemical mechanism). The free energy profiles obtained through these procedures are supported by independent experimental evidence: (1) steady-state kinetic constants, (2) solvent viscosity dependence, (3) spectral analysis of reaction intermediates, (4) equilibrium overshoots for progress curves measured in D 2O, and (5) the magnitudes of calculated intrinsic kinetic isotope effects. The free energy profiles for the enzyme are compared to those of the uncatalyzed and the PLP catalyzed reactions. At pH 6.9, PLP lowers the free energy of activation for deprotonation by 8.4 kcal/mol, while the inclusion of apoenzyme along with PLP additionally lowers it by 11 kcal/mol.
Details
- Title: Subtitle
- Alanine Racemase Free Energy Profiles from Global Analyses of Progress Curves
- Creators
- M. Ashley Spies - University of California, DavisJoshua J. Woodward - University of California, DavisMitchell R. Watnik - University of California, DavisMichael D. Toney - University of California, Davis
- Resource Type
- Journal article
- Publication Details
- Journal of the American Chemical Society, Vol.126(24), pp.7464-7475
- DOI
- 10.1021/ja049579h
- PMID
- 15198593
- ISSN
- 0002-7863
- eISSN
- 1520-5126
- Language
- English
- Date published
- 06/23/2004
- Academic Unit
- Pharmaceutical Sciences and Experimental Therapeutics; Biochemistry and Molecular Biology; Medicinal and Natural Products Chemistry
- Record Identifier
- 9984288724302771
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